Fortification of food with micronutrients such as iron is not a straightforward procedure. For instance iron induces very often unacceptable product alterations related to its discoloring and pro-oxidative properties. To avoid these alterations it is common to use insoluble iron sources, which are less chemically reactive than water soluble iron salts. However, these compounds generally have a reduced bioavailability, and hence lower nutritional value. It is clear though that bioavailability depends on many factors, such as food matrix and population age.
Another solution is encapsulation of iron, in order to physically prevent iron from interacting with other food ingredients. The iron compound is coated with a protective layer or embedded in a matrix, which constitutes a physical barrier to its diffusion or dissolution in the food matrix, reducing its reactivity. The release of iron is then triggered by pH, enzymatic cleavage or temperature changes.
Fat based encapsulates are not heat stable and they undergo phase separation in aqueous compositions. However, an advantage of such systems is the possibility to encapsulate iron sulphate, which is considered as the most bioavailable iron compound, and thus used as a reference for bioavailability comparisons. Other types of encapsulates are based on phospholipids and most of them deliver iron pyrophosphate, which is less bioavailable than iron sulphate.
Proteins like lactoferrins can chelate iron. However, such proteins impart an undesirable pink colour to the product. The high affinity for iron is also a characteristic of other proteins such as caseins or globular proteins. Remondetto et al. (2004) (Journal of Agricultural and Food Chemistry, 52, 8137-8143) has studied the iron release mechanism of globular proteins macrogels containing iron gelled by means of heat and ionic induction.
Surh et al. (2007) (Journal of Agricultural and Food Chemistry, 55, 175-184) describes water-in-oil emulsification processes. However, the drawback of applying water-in-oil emulsification process is the additional step needed to separate the microparticles and wash-out the oil.
It is also desirable to offer an iron encapsulate which does not imply the declaration of multiple ingredients. No such encapsulates exist today that can offer satisfactory performance in high moisture applications. From the numerous iron encapsulation systems from suppliers that were evaluated so far, Ferrazone (iron-EDTA) appears to be the best solution. However EDTA is not allowed in all countries.
Similar difficulties are encountered when other micronutrients are considered.
Therefore, it is desirable to offer a versatile fortification solution, which is adapted to several micronutrients.